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Apprentice answer

Why do loose duct liner pin heads fail inspection

2nd YearInsulation, Liner & CondensationStandard Correction

Loose or proud liner pins can catch dirt and let liner lift in the airstream. Flatten/secure them and repair liner facing per approved liner adhesive/spec before inspection closeout.

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Plain-English answer

Internal acoustic liner has to stay tight to the duct wall. If grip pins or heads stick proud into the airstream, they can catch lint/dust and create a spot where liner starts tearing loose.

Reach the area safely, flatten/secure the pin heads as allowed, repair damaged liner facing with approved adhesive/coating, and verify no loose insulation remains in the air path. Replace badly damaged liner sections if needed.

Ask Foreman

The lined duct at [location] has pin heads/liner fasteners sticking into the airstream. I checked for loose liner. Do you want them flattened and sealed with approved liner adhesive before inspection?

Verify before acting

Use this as training guidance. Foreman direction, approved drawings, project specs, manufacturer instructions, employer safety policy, and AHJ/code requirements always control the final answer.

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